While most of the conventional refection type liquid crystals devices display a black image on a white background, a black (or other colors such as blue) display on a clearly colored background is desired depending on its use. For example, it is well known that a black display on an yellow background is more recognizable than a black display on a white display, which is utilized in traffic signs. Display images such as black on a green background, black on a blue background, black on a pink background, blue on an yellow background and blue on a dark background are also appreciated mainly for the convenience of design. It is preferable that these background colors have brilliant luster.
Many method have been proposed to obtained color display images as described above. These methods utilize, for example, birefringent interference of ECB and STN, colored polarizers, diachronic dye and selective reflection of cholesteric liquid crystals. These conventional methods are described in the seventh chapter of "Handbook of Liquid Crystal Device (published by Nikkan Kogyo Shinbun Co.)" in detail.
These methods for displaying color images by the conventional liquid crystal devices have not been widely used by the reasons that the display images becomes dark, colors of the display images are limited, the reliability of display images are deteriorated or the production of the display devices is difficult. Besides, it was another problem that the reflective display images becomes dark when the transflective type display is performed by the conventional display device.